Optical recording media using a laser beam, etc. including laser discs are capable of recording and preserving informations at high densities and reproducing the recorded informations easily.
Laser discs generally comprise a disc base having provided thereon a thin recording layer, on which a laser beam condensed to a diameter of about 1 .mu.m is irradiated to carry out high-density recording. Upon absorption of energy of the irradiated laser beams, the recording layer undergoes thermal changes, such as decomposition, evaporation, dissolution, and the like to thereby make a difference in reflectance between the irradiated areas and the non-irradiated areas. Reproduction of the recorded informations can be carried out by reading the difference of reflectance.
Therefore, in order to effect high-density recording and precise reproduction, optical recording media are required to show efficient absorption of a laser beam having a specific wavelength used for recording and to highly reflect a laser beam having a specific wavelength used for reproduction.
Various structures are known for this type of optical recording media. For example, Japanese Patent Application (OPI) No. 97033/80 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") discloses a support having provided thereon a single layer of phthalocyanine dyes. However, phthalocyanine dyes have disadvantages, such as low sensitivity, high decomposition points which lead to difficulty in vacuum deposition, and very low solubility in organic solvents which lead to difficulty in coating for formation of the recording layer.
Japanese Patent Application (OPI) Nos. 83344/83 and 22479/83 disclose phenalene dyes and naphthoquinone dyes, respectively, to be coated as a recording layer. These dyes, though easy to evaporate in vacuo, show low reflectances. Low reflectances result in poor contrast in reflectance between the recorded areas and non-recorded areas, thus making it difficult to reproduce the recorded informations.
In addition, Japanese Patent Application (OPI) Nos. 24692/84, 67092/84, and 71895/84 disclose recording layers comprising cyanine dyes. The cyanine dyes have an advantage of easy coating but are inferior in light resistance and undergo deterioration due to light for reproduction.